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PATENTED JAN. 19, 1904.

'H. R; CASSEL'. BURGLAR ALARM FOR SAFBS.

APPLICATION FILED MAY 3, 1902.

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U ITED STATES Patented January 19, 1904.

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Letters Patent No. 749,8422, dated January 19, 1904.

sracmoa'rrou forming part of Application filed. May 3, 1902. .ierial No, 105,741- (No model.)

it may concern:

, Be it known thatI, HENRY RENNER CAssEL, .a citizen-of the United States of America, residing at Lond )n, England, have invented certain new and u: seful Improvements in Burglar- .Alarms for Safes, of which the following is a Specification.

My invention relates to a burglarnlarm for safes, vaults, or strong rc oms hereinafter comprehensiv 31y referred to'as safes. The

, safes must be rendered airtight, so that the -a central station distant 35- air within the chamber of the safe may be compressed or in thesurrour iding atmosphere.

I place insid e the chamber of the safe a mercury pressure gage and two wires of an electrical circuit. In this circuit is a resistancecoil and a sole inoid or electromagnet with an ironcore susp nded from'a balance-beam. As long as the nor mal' current is flowing through this'cir cuit th e magnetized core retains the balance-beam in its mean position; but when the-strength of the .current deviates from the normal or is cut ofi through the breaking of the circuit the core rises or falls, and one end of the balance -beam dips into a cup containing m ercury a nd completes another circuit, which causes an alarm-bell to ring and actuates a1 1 indicatc r to denote which safe has been tampe redwith. The making and breaking of one circuit is thus controlled by another circuit. The alarm apparatus may be placed at from the safe or at any other desired point.

Th e accompanying drawing represents a safe provided with my improved burglar-alarm.

, A is a safe furnished with an air-pump B and a baromete r-tube C, containing mercury.

The said tube may e of any'suitable form.

.Int0 the open end C of the tube C extend two wires E F in such manner ten is to the both )m of tube C and is submerged,

that the wire F exwh ile the wire E is shorter and does not dip into the mercury Under normal atmospheric pressure. The wire F'is connected to aresistanee D, also placed wi ahin the safe. Both wires pass out of the safe through an opening, which is made air-tight. Wire F is connected to one pole of a battery r'source of current (l VVithexhausted, as desired, thereby cre 1 ating apressui 'e in the safe different from that in the circuit or wire E, which is connected to the other pole of battery G, asolenoid H, haw inga coreI, is arranged. The core I is suspend ed at K from a metallic balance-beam K, piV--.

oted at K. The ends of the beam are bent downward and are adapted to dip into either or :e of two mercury-cups L L when the beam K is tilted. A wire Q connects the pivot K of beam K to one pole of a second battery or source of current M, and a Wire R, connects t'o'the other pole or said battery, leads to an alarm-bell O and an indicator P. The wire R then branches into two wires 8 and S, which lead, respectively, to the cup L and the cup When the safe is closed and the air exhausted by the pump B, the mercury at C will rise and make contact with the terminal of Wire E, so that a main circuit is closed in the fOlll iwing manner: The current passes from battery Gr through wire E, solenoid H, wire E, mercury at C, wire F, resistance D, wire F, back to battery G. This normal current will cause the core'I of solenoid H to rise to such a height that'it Willmaintain the balance beam in itshorizontal position. Consequently the balance-beam will be out of contact with both of the cups L L. If new the safe is tampered with, so as to admit air therein, the pressure becomes normal, wher upon the mar cury at C drops back into its f rnier position, thus breaking the contact at G and demagnetizing tlisolenoid H. The core then drops and pulls d own the beam K, thus making contact through the cup L and completing the second, circuit, which causes the bell O and the indicator P to operate. In this case the current passes from batteryM, through wire R, alarm-bell 0, wire R, indicator P, wires R and S, cup L, balance-beam K, pivotK', and wire Q back to battery M. It will readily be understood that the same action takes place when either one or both of the wires E F have been cut or when the current decreases. An attempt to .sl iort-circuit the wires or to con nect them with diately detected, because current determined by the resistance D retains the core I in a prearranged position, and

any increase of the current in the main circuit above the'aormal strength causes the core to another battery is also immethe-strength of the ':rise, and thus to make contact at L. 1 This.

burned into the tube vin the safe causes the mercury Willefiect the closing of a circuit that also causes the hell 0 and the indicator P to operate. This circuit is closed in the following manner: The current passes from battery M, through wire R, alarm-bell 0, wire R, indicator P, wiresR and S, cup L, balance-beam K, pivot K, and wire Q, back to battery M.

,If it be desired to work by compressed air instead of by rarefied air, the wire E is connected with a C at a suitable height. By forcing air into the safe 'the pressure to rise in the long leg of the tube 0 until the main circuit is completed Instead of employing a balance-beam K, a galvanometer may be used, thecircuit being closed through its needle and a movable fork whenever any tampering with the safe or with the main circuit is attempted, or other known indicating devices may be employed.

-' Any barometer-tube or manometer in which mercury is. altered by pressure can be employed in lieu of the barometer-tube C or any other mechanical device capable of recording pressure-for instance, an aneroid-box.

platinum. contact 0 Any desired -number of safes may be connected with the main battery-or other source of electricity and a central station where the alarm apparatus is placed being made with theindicatoi's to show which safe is being tampered with. Instead of alarm-bells, glow-lamps or other suitable devices may be employed to raise an alarm or to attract attention when the safe is interfered with.

I claim In a burglaralarm for safes, the combina' nesses. p

HENRY R, CASSEL. Witnesses:

WALTER J. SKERTEN, GEO. J. B. FRANKLIN.

, proper connectionsecondary circuits, substantially as speci- 

